Certain pressure sensing applications utilize semiconductor transducer chips that can be packaged in a header assembly to facilitate connecting the sensor assembly to a pressure port, manifold, or other interface for which pressure of a media is to be measured.
A standard method for installing a pressure transducer chip in a header/housing assembly is by adhesive bonding. In some applications, a relatively hard epoxy-type adhesive can secure the chip to the housing. In other applications, a relatively soft rubber or silicon-type adhesive can be utilized to secure the chip. In certain applications, such as in high-temperature environments, the chip can be secured using glass frit bonding. The use of such adhesives and/or bonding can enable assembly and packaging using standard high-volume semiconductor packaging techniques, which can include automated adhesive dispensing, glass frit dispensing, chip pick-and-place, and wire bonding/welding for making electrical interconnections between the sensor chip and the transducer header.
FIGS. 1-3 depict conventional sensor assemblies 100 in which a pressure sensor chip is bonded to a header of the sensor enclosure by an adhesive or a glass bond. FIG. 1, for example, depicts a cross sectional side-view of a conventional enclosed and oil-filled sensor assembly 100 having a sensor chip bonded to the header. FIG. 2 depicts a cross sectional side-view of a similar sensor assembly 200 having a sensor chip bonded to the header. In this conventional assembly 200, the bottom portion of the sensor chip is bonded to a header of the sensor enclosure by an adhesive or a glass bond, while the sensor enclosure is open such that a top portion of the sensor chip can be exposed to the local gas or fluid environment. FIG. 3 is an isometric representation of the sensor assembly 200, as depicted in and discussed with reference to FIG. 2.
While allowing for high volume manufacturing, the use of adhesive or glass frit bonding of the sensor chip to the transducer housing can introduce a source of measurement error through the various built-in, transferred, and/or temperature-related stresses. For example, static and/or dynamic stress can be transferred to the transducer chip directly from the adhesive (or glass frit) layer and/or from dimensional changes in the housing due to external pressure or thermal expansion of the various housing components and mounting layers.
A need still exists for sensor systems and methods in which a transducer chip can be secured within a housing while avoiding certain stress-related measurement errors that can happen with traditional mounting techniques.